B&A Mineracao has made a non-binding proposal to buy the remaining 70 percent it does not own of Rio Verde, which is focused on the exploration and development of fertilizer projects in Brazil, said the source, who is not allowed to speak about the plan on the record.

The source declined to detail terms of the proposal, such as the price offered for Rio Verde.

Rio Verde has a market capitalization of about $44 million, according to Reuters data.

A statement on Rio Verde’s website confirmed that the firm "is in negotiations with B&A regarding the potential acquisition of the company." Rio Verde added that it formed a committee and has hired financial and legal advisers to handle the process.

Agnelli and his partners at AGN Participações SA, a mining, fertilizers and logistics company, teamed up with BTG Pactual to found B&A in July. The executive was ousted from Vale , the world’s second-largest mining company, last year after a decade at the helm.

The plan signals B&A’s bet that fertilizers will thrive as demand for grains and protein grows while that for minerals and metals lags.

Analysts in Brazil have said that production and sales of food are not as vulnerable as demand for iron ore, copper and other metals to an economic slowdown in China - the world’s biggest consumer of raw materials.

Farm industry association Fiesp said on Tuesday that Brazil will import a record $18.5 billion in fertilizers and other farm goods in order to plant a record soybean crop.

B&A Mineração’s proposal follows the September purchase of a minority stake in Toronto-based MBAC Fertilizer Corp in September. The company has projects in the potash and rare-earth minerals sector in Brazil.

Agnelli returned to mining through AGN earlier in the year after a six-month break. AGN and BTG Pactual, which is controlled by Brazilian billionaire financier André Esteves, joined forces in the $500 million venture aiming to buy minerals, metals, fertilizers and logistics companies.